Preselection control device



Sept. 23,1947. w P,| EAR 2,427,792

PRESELECT ION CONTROL DEVICE Original Filed Feb. 25, 1942 v i- 7 2 v.

, iNVENTOR Ilka/1M2 Lam T314. Y "E F ATIORNEY Patented Sept. 23, 1947PRESELECTION CONTROL DEVICE William P. Lear, North Hollywood, Calif.,assignor, by mesne assignments, to Lear, Incorporated, Grand Rapids,Mich., a corporation of Illinois Original application February 25, 1942,Serial No. 432,195,,now Patent No. 2,355,381, dated August 8, 1944.Divided and this application December 20, 1943, Serial No. 514,956

3 Claims.

The present invention relates to a switch assembly particularly adaptedfor use in the preselection control mechanism covered by U. S. Patent2,355,381, issued on August 4, 1944, to the present inventor andassignee on an application filed February 25, 1942, of which thisapplication is a division. Switch mechanisms used heretofore for suchapplications have generally been relatively complicated and expensive aswell as unreliable in operation. The present invention provides a switchassembly including a pair of control switches, preferably of the snapaction type, operable by a cam which is operatively associated with theplungers of the switches. Simple and effective adjusting mechanism isprovided for adjusting the position of the switches with respect to theoperating cam.

Normally, the cam is in a neutral position in which both switches areopen. Upon displacement of the cam a minute amount in either direction,one or the other of the switches is closed to effect a controloperation. When the control operation is completed, the cam is restoredto its neutral position which effects opening of the previously closedswitch.

The advantages, features and capabilities of the switch assemblyinvention will become more apparent from the following description of apreferred embodiment thereof, illustrated in the accompanying drawings.In the drawings:

Fig. 1 is a sectional elevation of apparatus embodying the invention;

Fig. 2 is a section taken along line '2--2 of Fig. 1;

Fig. 3 is a section taken along line 3--3 of Fig. 1; and

Fig. 4 is a section taken along line 4--4 of Fig. 3.

The control head depicted in sectional elevation in Fig. 1 comprises acasing fitted with a back plate 16. A control knob ll extends fromcasing 15. A pointer I8 is secured to knob H, with a dial arrangedbehind. Dial 2D is provided with suitable markings for comparison with areference mark, not shown, suitably arranged on the casing. Theperiphery of dial 29 is knurled to facilitate its manual adjustment.

An indicating lamp 23 is arranged on casing l5. Electrical cable l9detachably connects the electrical section of control head 15 with acircuit to be controlled.

A worm gear 33 suitably driven by a worm not shown, is secured to afriction plate through hub 34 of gear 33 and countersunk screws 36.Friction plate 35 is juxtaposed with the dial 20.

A spring washer 31 is interposed between housing l5 and friction plate35, urging plate 35 against dial 20. A control shaft 49 extends throughdial 20, friction plate 35, hub 34, and gear 33. Control knob I1 issecured to the outer end of shaft 40 by set screw 38. The other end ofshaft 40 has an extended head portion 4|.

An insulation disk 42 is secured to head 41 by rivets 43. A retainingring 44 is secured to shaft 40, against which spring washer 45 presseson dial 20.

Spring washers 31 and 45 thus press dial 20 and plate 35 into firmfrictional engagement. Spring washer 45 also biases disk 42 into firmfrictional engagement with worm gear 33 through shaft 40. Thus whencontrol knob 11 is rotated, disk 42 is correspondingly directly turned.Despite th'e frictional coupling of disk 42 and worm gear 33, gear 33remains stationary with dial 2!] when disk 42 is turned, since gear 33is in engagement with a worm. Also, if dial 20 is manually rotated, itwill move with respectto plate 35, which also remains stationary withgear 33. The zero adjustment of dial 20 is readily accomplished bymanually turning dial 23 until its zero 0 marking corresponds with thereference marking on the casing.

Insulation disk 42 contains a pin 15 which is engageable with forkedends 14 of cam clevis 16, as shown particularly in Figs. 1 and 2. Clevis16 is secured to clevis shaft 11, rotatably arranged in bearing 18. Theother end of clevis shaft 11 carries switch cam 80, forming part of thisinvention switch assembly as shown particularly in Fig. 3. Switch camhas a lower triangular shaped portion 8| and an upper circular camportion 82. Switch cam 80 is arranged between switch units 83 and 84 insuch manner as not to press or actuate switch plungers 85 and 86 when inthe neutral or central position shown in Fig. 3. The type of switchknown in the art as micro-switch is preferred for the switches 83 and84, wherein the plungers 85 and 86 require only small pressure, and needbe depressed only a small distance to effect the switching ofcomparatively large currents.

A pin 81 projects from cam 80 centrally; above clevis shaft H. A springpost 88 is fastened to fixed plate 90 secured with housing I5 by screwstuds 9|. A spring 93 is stretched between pin 81 and spring post 88.Spring 93 produces a toggle action, keeping switch cam 80 in unstableequilibrium in the central neutral position, or displaced to the fullright or left positions off center, corresponding with movementsimparted to the clevis. Spring 93 stabilizes the action of switch cam 80against vibration or mechanical shock. Stops 94 and 95 limit the turningof cam clevis 16, as shown in Fig. 2.

Switch units 83 and 84 are provided with springs 91 and 98 respectively.One end of the springs is secured to plate 90. The other ends of springs91 and 98 are arranged in holes IM and I02 provided in switches 83 and84. The springs 91, 98 mechanically bias the switches towards cam 80.Adjustable stops I04, I05 limit the inward positions of switches 83, 84and their corresponding plungers 85, 86. Stops I04, I05 are hexagonalheaded screws threaded into bosses I 06--I0"I on plate 90. The settingof heads I04, I05 is adjusted by a suitable wrench, to predetermine thelateral position of plungers 85 and 86 with respect to the periph'eralsurface of switch cam 80.

The vertical adjustment of switches 83, 84 is performed by eccentricbushings I08, I09 secured respectively to stud screws IIO, III. ScrewsIIO, III extend into plate 90. The screws IIO, III and the bushings I08,I09 pass through openings in the switches 84, 85, as indicated in Fig.4. By rotating adjusting stud screw 0 with bushing I08, switch unit 83may be correspondingly raised or lowered, for adjusting the position ofits plunger 85 vertically with. respect to cam switch 80. Similarly,plunger 86 of switch unit 84 is adjusted by stud and bearing I09, III.

counterclockwise rotation of knob I! through an arc displaces disk 42,turning clevis I8 clockwise through pin I5. Switch cam 80 accordingly islikewise rotated clockwise to cause plunger 86 to be depressed from itsnormal position to close the circuit of switch 84.

When pointer I8 is manually moved over scale 20 in a clockwise directioncausing a counterclockwise rotation of cam clevis I8 and hence of switchcam 80, plunger 85 of switch 84 is thereupon depressed to establish acircuit through this switch. 7

While the switch assembly has, for purposes of illustration, beendescribed in my Patent 2,355,- 381 as incorporated in an antennacontrol, it is generally applicable to any circuit. Furthermore,

while a, specific embodiment of the invention has' been shown anddescribed in detail to illustrate the applicationof the principlesthereof, it will be understood that the invention may be otherwiseembodied without departing from such principles.

What is claimed is:

1. An electric switch assembly comprising a base; a pair of switcheseach having an operatin plunger; individual means pivotally mountingeach switch on said base; a cam oscillatably mounted on said basebetween said switches; said operating plungers engaging opposed surfaceportions of said cam; such pivotal mounting means comprising individualcircular cam means engaging a circular aperture in each switch andeccentrically mounted on a pivot secured to said base; said circular cammeans providing for adjustment of said switches with respect to saidpivot to substantially align said operating plungers; and

. a pair of springs each having one end engaged with said base and theother end engaged with a switch, said springs urging said switches toward said cam.

2. An electric switch assembly comprising a base; a pair of switcheseach having an operating plunger; individual means pivotally mountingeach switch on said base; a cam oscillatably mounted on said basebetween said switches; said operating plungers engaging opposed surfaceportions of said cam; such pivotal mounting means comprising individualcircular cam means engaging acircular aperture in each switch andeccentrically mounted on a pivot secured to said base; said circular cammeans providing for adjustment of said switches with respect to saidpivot to substantially align said operating plungers; a pair of springseach having one end engaged with said base and the other end engagedwith a switch, said springs urging said switches toward said cam; andadjustable means limiting the movement of each switch toward said cam.

3. An electric switch assembly comprising a base; a pair of switcheseach having an operating plunger; individual means pivotally mountingeach switch on said base; a cam oscillatably mounted on said basebetween said switches; said operating plungers engaging opposed surfaceportions of said cam; such pivotal mounting means comprising individualcircular cam means engaging a circular aperture in eachswitch andeccentrically mounted on a pivot secured to said base; said circular cammeans providing for adjustment of said switches with respect to saidpivot to substantially align said operating plungers; a pair of U-shapedsprings each looped around one of said pivots and each having one endengaged with said 'base and the other and engaged with a switch,- saidsprings urging said switches toward said cam; and adjustable meanslimiting the movement of each switch toward said cam.

WILLIAM F. LEAR.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 588,428 Heck Aug. 17, 1897904,906 Wiegand Nov. 24, 1908 2,388,365 Thorp Jan. 4, 1944 2,033,417Dezotell Mar. 10, 1936 2,094,319 Faust Sept. 28, 1937.

